Added some new comments + some helpful old comments from a time before the interface revision

include/astaroth.h

@@ -41,27 +41,44 @@ extern "C" {
 #define acLoadDeviceConstant(x, y) acGridLoadConstant(STREAM_DEFAULT, x, y)
 */
 
+/** Allocates all memory and initializes the devices visible to the caller. Should be
+ * called before any other function in this interface. */
 AcResult acInit(const AcMeshInfo mesh_info);
 
+/** Frees all GPU allocations and resets all devices in the node. Should be
+ * called at exit. */
 AcResult acQuit(void);
 
+/** Synchronizes a specific stream. All streams are synchronized if STREAM_ALL is passed as a
+ * parameter*/
 AcResult acSynchronizeStream(const Stream stream);
 
+/** Loads a constant to the memories of the devices visible to the caller */
 AcResult acLoadDeviceConstant(const AcRealParam param, const AcReal value);
 
+/** Loads an AcMesh to the devices visible to the caller */
 AcResult acLoad(const AcMesh host_mesh);
 
+/** Stores the AcMesh distributed among the devices visible to the caller back to the host*/
 AcResult acStore(AcMesh* host_mesh);
 
+/** Performs Runge-Kutta 3 integration. Note: Boundary conditions are not applied after the final
+ * substep and the user is responsible for calling acBoundcondStep before reading the data. */
 AcResult acIntegrate(const AcReal dt);
 
+/** Applies periodic boundary conditions for the Mesh distributed among the devices visible to the
+ * caller*/
 AcResult acBoundcondStep(void);
 
+/** Does a scalar reduction with the data stored in some vertex buffer */
 AcReal acReduceScal(const ReductionType rtype, const VertexBufferHandle vtxbuf_handle);
 
+/** Does a vector reduction with vertex buffers where the vector components are (a, b, c) */
 AcReal acReduceVec(const ReductionType rtype, const VertexBufferHandle a,
                    const VertexBufferHandle b, const VertexBufferHandle c);
 
+/** Stores a subset of the mesh stored across the devices visible to the caller back to host memory.
+ */
 AcResult acStoreWithOffset(const int3 dst, const size_t num_vertices, AcMesh* host_mesh);
 
 #ifdef __cplusplus